Frame loads accuracy assessment of semianalytical multibody dynamic simulation methods of a recreational vehicle

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Frame loads accuracy assessment of semianalytical multibody dynamic simulation methods of a recreational vehicle Nicolas Joubert1,2 · Maxime Boisvert1,2 · Carl Blanchette1,2 · Yves St-Amant3 · Alain Desrochers1,2 · Denis Rancourt1,2 Received: 10 September 2019 / Accepted: 16 July 2020 © The Author(s) 2020

Abstract The design of a vehicle frame is largely dependent on the loads applied on the suspension and heavy parts mounting points. These loads can either be estimated through full analytical multibody dynamic simulations, or from semi-analytical simulations in which tire and road sub-models are not included and external vehicle loads, recorded during field testing, are used as inputs to the wheel hubs. Several semi-analytical methods exist, with various modeling architectures, yet, it is unclear how one method over another improves frame loads prediction accuracy. This study shows that a semi-analytical method that constrains the vehicle frame center of gravity movement along a recorded trajectory, using a control algorithm, leads to an accuracy within 1% for predicting frame loads, when compared to reference loads from a full analytical model. The control algorithm computes six degrees of freedom forces and moments applied at the vehicle center of gravity to closely follow the recorded vehicle trajectory. It is also shown that modeling the flexibility of the suspension arms and controlling wheel hub angular velocity both contribute in improving frame loads accuracy, while an ac-

B N. Joubert

[email protected] M. Boisvert [email protected] C. Blanchette [email protected] Y. St-Amant [email protected] A. Desrochers [email protected] D. Rancourt [email protected]

1

Department of Mechanical Engineering, Université de Sherbrooke, Sherbrooke, Canada

2

Centre de Technologies Avancées BRP, Université de Sherbrooke (CTA), 3000 Boulevard de l’Université, Sherbrooke, QC, J1K 0A5, Canada

3

Department of Mechanical Engineering, Université Laval, Québec, Canada

N. Joubert et al.

quisition frequency of 200 Hz appears to be sufficient to capture load dynamics for several maneuvers. Knowledge of these loads helps engineers perform appropriate dimensioning of vehicle structural components therefore ensuring their reliability under various driving conditions. Keywords Load prediction · Semi analytical · Wheel force transducer · Flexible multibody modeling · Sensitivity study · Frame loads

1 Introduction Knowledge of vehicle frame loads is of interest in the design process, and the sooner the loads are determined, the easier it is to make appropriate changes to a vehicle design. Determination of these loads with a good degree of confidence helps generate more realistic structures in the course of the first frame design iterations [1]. Vehicle frame loads at the suspension and heavy parts mounting points can be determined by using load sensors installed at the frame mounting points (suspension arms bushings, engine mounts, shock absorbers bush